Hallo Gabriel,

in former times (and even today) R-2R ladder was widely used in electronics. I have seen it many times in tuners or video-recorders, where it was directly connected to some 8bit wide port of simple microcontroller to produce certain control voltages.

R-2R ladder is also used in many integrated DACs, like AD7533 (10bit resolution), AD7537 (even 12bit resolution).

The major handicap of discretely built R-2R ladder circuit by the help of some 8bit buffer like 74HC374 or similar is, that finite resistance of source drain channel of internal NMOS and PMOS transistors are eroding precision: Even if you use errorless resistors for your R-2R ladder source drain channel resistance of about 25...50Ohm will add some unavoidable error.
The only methode to decrease this mistake is to choose rather high values for R and 2R, so that it's influence is minimized. R >= 50kOhm is a good choice.

Even if R is choosen very high, long term drift of normal metal film resistors will result in some error after some time. Although most 'candidates' will show less than 0.1% deviation after 2 years at 40°C, you are not shielded against certain 'deserters', which can show drastical deviation. Although in the last years metal film resistor have become very stable and even 0.1% tolerance types are available today at acceptable prices, there's always a certain probability of having some deserter.
Don't forget also to have a look at tempco specification! Much less than 50ppm is required, if choose of 0.1% tolerance resistors shall make any sense.

Three other disadvantages are to be focused:

- Some designs show rather high glitch energy. Keep in mind, that also noise on Vcc is directly 'channeled' to output. And for 74HCMOS this can be quite high.

- At higher temperatures leakage current from succeeding circuitry can make trouble with high value R and 2R resistors, resulting in some temperature dependant offset.

- 'Reference' voltage is normally identical to Vcc, which can also show rather high drift, especially when simple three-pin voltage regulators are used.

Concluding: R-2R ladder can be used, when very high precision, low long term drift and pure monotonicity is NOT an issue, especially, when less than 8bit resolution is required. In all other cases real DACs should be used.
Keep in mind, that in feedback applications you can end up with heavy oscillation, when DAC shows monotonicity error!! Then, keep of any robotics application...

Kai